Safe's Electric Bike Project #002

[dirty_d]

right but with motor current limiting the battery current will always be less than or equal to the motor current. same as battery current limiting except the battery current will be even lower at some points.

 

[v_tach]

Don't give people unrealistic expections of how much effort is involved... if you do they will become frustrated and give up. I'm hoping that people will realize that it requires real work and do it themselves anyway.

Its possible and easy enough. I've been making plug molds for large scale R/C aircraft for years using the foam process. I've also made molds and body panels for various other projects such as experimental aircraft, custom automobiles, and go karts. I think I have the experience to know what is possible and the pros and cons of many different choices. Your project so far based on the pictures is incredibly simple. It wouldn't be worthwhile for me to spend two days on a single part for the plug alone. You could have the actual part pulled in two days.

2. Never sand with your bare hands because that just repeats the errors that already exist. Use a sanding block and that way you are only sanding off the high spots and not digging the low spots any deeper.

That line right there indicates your complete inexperience with such work. You shouldn't be so doubtful of others if you have no practical experience of your own.

 

[Lowell]

I prefer using stacked foam myself, but I applaud Safe for his creativity and motivation on this project.

 

[safe]

2. Never sand with your bare hands because that just repeats the errors that already exist. Use a sanding block and that way you are only sanding off the high spots and not digging the low spots any deeper.

That line right there indicates your complete inexperience with such work.

Okay, I'm curious now...

Are you saying that block sanding does not tend to smooth out ripples easier than hand sanding? The problem with hand sanding is that since your fingers tend to produce uneven pressure the sandpaper tends to dive down into the low spots and take away material that you don't want to touch.

So are you saying that you have mastered some hand sanding technique that gets past this problem?

I'm open to learn... I've done several projects like this (and also used to build radio controller gliders a long time ago) and consider that I've heard of or seen most of the techniques out there.

Given the complexity of this shape and the uncertainty of how it will end up (and the need to be within about 1/4 an inch of perfect to make it fit) I tend to reject the idea of building ANYTHING that doesn't attach directly to the bike. Anything free form is simply too likely to produce slight errors in the translation to make work.

Foam is nice, but that's the foundation part which is pretty simple. Most of the work is the surface level bondo which involves a lot of careful eyeballing to get the shape just right and the eventual glassy smooth finish. Ideally you should be able to see your reflection in the final result and not have much distortion.

But hey, there are certainty body finish experts out there that I'm sure have more experience and can do it faster than I can. All that matters is the the final result is good. The time it takes is just the time it takes... it's "whatever" the project demands.

 

[Toorbough ULL-Zeveigh]

Every book on bodywork, be it scale models or full-size cars stress the point of not hand sanding. Of course advice from a book is neccesarily directed towards the beginner. Freehand I would think would require a lot of talent & artistic skill in addition to a lot of experience.

 

[safe]

Block sanding is also easier on your hands.

 

[dirty_d]

it would be interesting to see what your finished bike's CdA value is and how it compares to other bikes without fairings. if you ride it some constant speed and watch how much current is going through the motor you can calculate the forward force on your bike(which the air drag force will be equal to not considering mechanical friction), from there you know drag, velocity, and the density of air so you can solve for CdA.

 

[safe]

it would be interesting to see what your finished bike's CdA value is and how it compares to other bikes without fairings.

I know by the top speed in various gears how my existing bike compares. When I sit upright the aerodynamics makes it hard for me to get past about 32 mph on the flat. In a tight tuck my top speed jumps up to 38 - 40 mph. I suspect that when I make a few spare fairings with the new bike and slap a set on the old bike that my top speed on the flats will climb a mph or two. So I expect the "with fairing" #001 bike to be in the 40 - 42 mph range.

From these numbers I've already "reverse engineered" what my approximate numbers are for the non-fairing #001 bike in a tuck:

Cd = 0.7
Frontal Area = 0.25 m^2

A regular upright mountain bike is:

Cd = 0.9
Frontal Area = 0.5 m^2

Most of the aerodynamic advantage is the fact I'm tucked into a tight ball. With no actual fairing I'm still getting an advantage just by reducing the frontal area.

 

[safe]

Sanding Progress

The weather is turning nicer, so it's becoming easier to work again. Here's a look at how things are developing. I've been changing the shape in subtle ways and making sure that everything is just right. It's important that every bend is the same on both sides. I'm not quite to the level of primer paint (the final step) but it's getting close.

 

[Beagle123]

Wow. Nice job safe. How much will your bike weigh when you're done?

 

[safe]

Wow. Nice job safe. How much will your bike weigh when you're done?

It depends on my battery pack choices.

The minimal LiFePO4 solution is only 11 lbs.

The NiMh solution is about 30 lbs, but has three times the range.

The base weight is going to be something like:

1. Frame and Fork - 20 lbs
2. Motor - 10 lbs
3. Fairings - 10 lbs
4. Other - 20 lbs

So a base of about 60 - 70 lbs which means overall weight should come in under 100 lbs which compared to my 140 lb SLA bike will seem great. The frame could handle 50 extra pounds of batteries or more so the ability to add extra batteries and not have the bike's ability to get me around safely compromised is a nice thing.

Flat land top speed is almost entirely about aerodynamics... extra weight only makes a difference going up a hill and on the downhills the weight actually makes you go faster. Here in the midwest hill climbing ability isn't a big deal, though we do have very short and steep hills (about 50 feet high) that can be demanding.

Note: I pretty much finished the sanding and am ready to move on to the primer paint which I'll need to buy tomorrow morning. Once you get the primer on you can then focus on anything that doesn't look right. So far it's working out really well and the resulting fairing should be very good.

No picture today...

 

[safe]

Primer Paint

It's looking pretty good. The primer paint has exposed a few problem areas, but overall it has turned out well. I rethought the underside of the shape and in the middle area near where the shock sticks out. I actually added an underside to it all that is smooth and will allow me to make a final product that has a little lip on the bottom. There's nothing more annoying than a piece of fiberglass that just sort of stops and leaves a sharp edge. An edge like that tends to get chipped paint and the fiberglass tends to fall apart. Plus it's hard to get a smooth looking curve if you don't build that smoothness into the mold.

The actual molds will be two pieces. One half will go from the back up underneath the seat just about to where the shock is located. The front half will go from the front all the way through the seat up to about an inch past the upper lip of the seat. The attachment of the two will be a shape that roughly follows the seat curve from top, around the sides and then down.

 

[dirty_d]

holy crap that looks awesome, all you have left is the front fairing now right?

 

[deecanio]

aye, thats some lovely work there safe

cheers

D

 

[safe]

holy crap that looks awesome, all you have left is the front fairing now right?

It's getting there. Yes, I still need to create the front fairing and I'll need to decide on which motorcycle clear bubble that I want to use as a base. From what I can tell all the clear bubbles (windscreens) for motorcycles are running about $70 on average and the clearance items are running about $50. It's important for me to standardize on something that is affordable because that really jacks up the overall price of the front fairing unit. I suppose I could use a simple piece of clear plastic that is cut and bent to approximate the shape (what I did in 1980 on my first bicycle road racers) but I'd kind of like to actually go that last step and get a real front fairing bubble this time.

They have two kinds:

1. Regular large bubble shape.

2. Double bubble (small on the inside and larger on the outside) that is supposed to be better in that it reduces turbulence around the helmet area.

After that, don't forget that I still have to create the MCL circuit to control the motor. I have a 48 Volt 100 Amp controller that would destroy my motor very fast if it isn't limited with MCL. (down to 40 or 50 amps)

I still haven't even decided on the batteries yet either, so that's another area to think about.

Last year I ended the summer with my #001 Project just barely able to do a test ride. Now the #001 Project is fully debugged and running great (rode it 10 miles today and am up to around 2,250 miles) so I suspect this #002 Project will be in it's first testing phases as the riding season closes down. It will be next spring when the refinement begins and I discover what the real limits will be.

I expect good things with this bike...

 

[Beagle123]

Looks great safe. I beleive that your bike will be a near perfect design. I don't think anyone could squeeze much more performance out of a bike.

Where could it be improved?

Weight? No.
Aero-dynamics? Maybe a bit if you happened to own a wind tunnel?
Motor? a little bit.
Transmission? Maybe a little

I'd really be interested to see how close your bike gets to theoretical maximums. I bet its really good.

Can you imagine if a company like Toyota invested in building bikes like this? WIth their R&D budget, they could optimize every detail, and if the transmission was operating at only 85%, they build a new one fram scratch before they'd allow the energy waste.

I guess I'm dreaming outloud.

 

[Lowell]

Weight can always be saved, but the cost goes up. Look at the lengths the weight weenie's will go to in order to save a gram or three. Any frame made of steel is overweight to begin with, but steel is easy to work with so it has it's place.

http://weightweenies.starbike.com/

 

[safe]

Weight is my bikes worst area right now. At a starting weight of 17 lbs for the frame that's way above where it should be. If it weren't for the nifty concept of placing the batteries inside the frame I could have done something more like what Dirty D has done. Actually my Project #003 will use some lighter weight parts (smaller tires, lighter frame that will actually allow pedaling) and still be compatible with the fairings I'm building. Actually all three projects will be sporting the same identical fairings in time.

The future for me will be to get into some nice suspension front and rear. I'm talking about true oil dampened suspension and forks that have some large diameter tubing and real rigidity. The price will go up as I will be getting into more expensive components, but a future Project #004 will still be using the same fairings. I'm pretty much "set" on the overall geometry with 52" being the standardized wheelbase.

But before I do a #004 I need to do a #003 and my #002 isn't even done yet. And #001 will get the retrofitted fairings, so it's like a continuous process that always evolves.

The #003 will really explore the use of pedaling with these fairings to see how well the "sit and stand" riding technique works in practice.

I use the "Thomas Edison" assembly line technique for innovation. Just keep trying new stuff and see what works...

"Survival of what fits and does not fail" - Charles Darwin "like" phrase.

 

[dirty_d]

where on earth did you find those 24" wheels? all the bike part sites i go to only have 26" wheels. i need two 24" wheels with disc brake hubs, and as cheap as possible, it seems like the online stores only sell the very expensive stuff for people who are really serious cyclists. have any tips? i might just end up using 26" wheels with regular sized tires.

 

[safe]

where on earth did you find those 24" wheels? all the bike part sites i go to only have 26" wheels. i need two 24" wheels with disc brake hubs, and as cheap as possible, it seems like the online stores only sell the very expensive stuff for people who are really serious cyclists. have any tips? i might just end up using 26" wheels with regular sized tires.

I bought three 24" bikes that had dual disc brakes for $100 each. Since then I've been cannibalizing those bikes. I went to Toys R Us of all places. (you should have seen the looks of the mothers in the store figuring I must be a child molester or something)

Try searching online... I had to have the Toys R Us people transfer them from other stores just to get them. That particular model is out of stock.

I also got lucky in that my neighbors kid threw a perfectly good 24" bike into the garbage and so I "dumpster dove" to get it. I have no pride... :lol:

 

[safe]

Beginning the Front Fairing

I feel like going ahead with the Front Fairing mold first rather than getting into the fiberglass right now. All I've done so far is take the cardboard box that I made for the extra battery location and added some fine mesh wire screen and then some bondo on top. From this base I'll start adding other wire and eventually the Front Fairing will come into existence.

I've been riding the #001 bike a lot (sometimes three times a day) and relaxing on the long Labor Day weekend. Eventually I'll get a full effort going again on this Project #2, but it's becoming pretty clear that this bike (like the last one before it) will not be ridden until next spring. It just seems to work out that way... by the end of the summer your project nears completion but the time runs out. That's okay... there's always next year and for now there's always the #001 bike to ride. Plus, this one is so much more complex than the last bike that a lot of stuff still needs to be done. (the hours required are probably double the last bike)

It's still necesary for me to go back over the rear fairing and carefully look for and correct all the small imperfections in the mold. That takes time and patience so sometimes it's nice to simply switch to something else for a while and then get back to the finest level of detail later. It's that last 10% that really makes something either really nice or just sort of homemade and crummy looking.

 

[safe]

The September Blues

I've been trying hard to ride the last miles I can on my Project #001 bike to reach 2,500 miles before winter arrives. Right now I'm up to 2,391 miles so I don't have that far to go. This project is "there" staring at me and nagging by saying:

"Why couldn't you have gotten me done before winter?"

I end up having to apologize to "her" for not getting "her" done faster. "She" has been a lot of work, in fact, it's been most of my free time since June. The realization that the summer is ending and that there's going to be a long wait until next year makes me start to find ways to not work on "her" as much. The weather is really nice and after the oppressive heat that almost forces you into activity the mood is now one of relaxation and rest.

So I'm in a sense "cheating" on "her" and flirting with nice weather and bike #001... I guess all of us guys are scum... :wink:

I suspect that #001 knows about #002 and boy what a cat fight that would be if they ever met! I wonder if this could make a good Jerry Springer show? :lol:

 

[xyster]

So I'm in a sense "cheating" on "her" and flirting with nice weather and bike #001... I guess all of us guys are scum... :wink:

I suspect that #001 knows about #002 and boy what a cat fight that would be if they ever met! I wonder if this could make a good Jerry Springer show? :lol:

This is the most disturbing case of sexual-objectification transference to an animate object I've ever witnessed. See a shrink, Safe. Then after you're fixed, get a date.

 

[dirty_d]

at least its not animals.

 

[xyster]

at least its not animals.

:lol: A really good point. I was waiting for safe to retort by quoting some of my comments of a similar ilk. Then I was going to...oops, better to keep the aces in my sleeve. :wink: